Supramolecular Synthons and Hydrates in Stabilization of Multicomponent Crystals of Nicotinamide and Isonicotinamide with N-Containing Aromatic Dicarboxylic Acids

Multicomponent crystals (either cocrystal or salt) of nicotinamide (nicotinic acid amide) and isonicotinamide with various nitrogen heterocycle-containing aromatic dicarboxylic acids, namely, 3,5-pyrazole dicarboxylic acid (pzdca), dipicolinic acid (dpa), and quinolinic acid (qna), have been synthesized and characterized by single-crystal diffraction and thermal studies. The nicotinamide (nic) and isonicotinamide (isonic) cocrystals with 3,5-pyrazole dicarboxylic acid (1 and 2, respectively) possess four different heteromeric supramolecular synthons in each cocrystal, which is rare. The nicotinamide dipicolinic acid cocrystal, 3, showed formation of water-bridged assembly, whereas isonicotinamide-dipicolinic acid cocrystal, 4, led to a six-component assembly through the isolated solvent water molecules occupying the interstitial positions. The salt formed from quinolinic acid with nicotinamide 5 has a hydrogen-bonded 1D water chain in its crystal lattice, whereas quinolinic acid with isonicotinamide resulted in formation of 6 with 2D sheets of multiple heterosynthons. Thermal studies show evaporation of various water molecules with a trend that has relevance to their hydrogen-bonding environment in the multicomponent crystal.